feat: DTOs and interfaces

Services/Interfaces/IRuleValidationService.cs

@@ -0,0 +1,10 @@
+using GamificationService.Models.Database;
+
+namespace GamificationService.Services.Interfaces;
+
+public interface IRuleValidationService
+{
+    Task<bool> ValidateMissionRankRulesAsync(Guid missionId, Guid playerId);
+    Task<bool> ValidateRankAdvancementRulesAsync(Guid playerId, Guid targetRankId);
+    Task<IEnumerable<MissionRankRule>> GetApplicableRankRulesAsync(Guid missionId);
+}